The mother of a three-month-old baby kidnapped from their San Francisco Bay Area home said a woman arrested in the case met the family at church and had been spending a lot of time with them.

Carolina Ayala told Spanish language television stations that after she gave birth, suspect Yesenia Ramirez was a constant presence at her home.

"She would go to my house a lot, she always wanted to be there," Ms Ayala said in Spanish in an interview with KTST-TV, a Telemundo affiliate.

Ramirez, 43, was arrested for allegedly kidnapping Brandon Cuellar along with Baldomeo Sandoval and Jose Portillo, who police said entered the family's second-floor San Jose apartment on Monday and took the baby while his grandmother unloaded shopping.

Sandoval, who Ms Ayala said is Ramirez's husband, was released without charges on Thursday, San Jose Police officials said in a statement.

"Details regarding Sandoval's involvement with this case have come to light and he will not be facing charges at this time," it said.

Ramirez and Portillo were arraigned on Thursday on kidnapping, felony burglary and conspiracy charges and are being held without bail.

Lawyers with the Santa Clara County public defender's office, which is representing Ramirez and Portillo, did not immediately return a phone message from The Associated Press.

Portillo, 28, was caught on CCTV carrying a baby car seat and small blanket and walking towards the apartment, police said.

They said the motive for the kidnapping is still under investigation.

On Monday, Ramirez offered to buy supplies for the baby and drove the baby and his grandmother, Victoria Mejia, to a shop and back, Ms Mejia told the Telemundo affiliate.

Police said Ramirez had been communicating with Portillo moments before he took the baby and drove away.

Ms Ayala said she was at work cleaning a home when her sister-in-law called her to let her know her child was missing.

"I felt like half of my heart had left with him. I felt like I died," Ms Ayala told KDTV-TV, a Univision affiliate.

Police found the unharmed baby on Tuesday inside a home where Portillo lived.

Ms Ayala was reunited with her son hours later, a moment she described as "having my soul return to my body".

"I cried out of joy, I cried until I got tired of crying," she told Telemundo 48.